Here is an example of my inventory spreadsheet:
DATA TABLE
Type Amount Sold
1 15
2 10
3 5
1 6
3 10

SUMMARY TABLE
Type Amount Remaining
1
2
3

Here is what I need to do and can't figure out:
In the Data Table, I enter the amount sold by type on a new row each time
there is an order. I would like the Summary table to populate for a quick
view based on the information entered into the Data Table. If the total
inventory is 100, how do I get the Amount Remaining in the Summary table to
populate as I enter in the quantities sold by Type sold? Example: The first
entry is for 15 Type 1's sold, so the table should have read 85, then when I
entered the next sale of 6 for Type one, the summary table should reflect 79.


THANKS!